本文件涉及使用具有指定CIE标准光源和光电探测器的单光束光度计测定平面透明和基本无色塑料在光谱可见区域的总透光率。本文件不能用于含有荧光材料的塑料。本文件适用于厚度不超过10 mm的透明模塑材料、薄膜和片材。注1:总透光率也可通过双光束分光光度计测定，如ISO 13468-2所示。然而，本文件提供了一个简单但准确、实用和快速的决定。该方法不仅适用于分析，而且适用于质量控制。注2:基本上无色的塑料包括淡色的塑料。注3:如果仪器能够容纳厚度大于10 mm的试样，则可测量厚度大于10 mm的试样，但结果可能与使用厚度小于10 mm的试样获得的结果不可比。

This document covers the determination of the total luminous transmittance, in the visible region of the spectrum, of planar transparent and substantially colourless plastics, using a single-beam photometer with a specified CIE Standard light source and photodetector. This document cannot be used for plastics which contain fluorescent materials. This document is applicable to transparent moulding materials, films and sheets not exceeding 10 mm in thickness. NOTE 1 Total luminous transmittance can also be determined by a double-beam spectrophotometer as in ISO 13468-2. This document, however, provides a simple but precise, practical and quick determination. This method is suitable for use not only for analytical purposes but also for quality control. NOTE 2 Substantially colourless plastics include those which are faintly tinted. NOTE 3 Specimens more than 10 mm thick can be measured provided the instrument can accommodate them, but the results might not be comparable with those obtained using specimens less than 10 mm thick.